Turning a single stage temp controller into two stage

I'm not sure if anyone has covered this but I bought a Johnson Controls System 450 for my fermentation fridge.

Even though it was a two stage I figured I could use one of the relays and use it for two stage control.

It dawned on me that if I just snapped off the connecting tab on my 110v outlet to isolate each receptacle I could use it for two stage control.

Is anyone doing this?

dmfa200 said:

I'm not sure if anyone has covered this but I bought a Johnson Controls System 450 for my fermentation fridge.

Even though it was a two stage I figured I could use one of the relays and use it for two stage control.

It dawned on me that if I just snapped off the connecting tab on my 110v outlet to isolate each receptacle I could use it for two stage control.

Is anyone doing this?

Click to expand...

I'm confused. A single stage controller only has one relay, and can not be converted to two stage use. You can control any number of different things with a single stage controller, switching between functions as needed, but can not simultaneously control two different outputs at the same time (which is what dual stage means). The Johnson control system 450 is neither a single stage or dual stage unit, and in fact has up to 10 outputs.

The reason for my question is that the system 450 controller has single pole double throw relays.

What I did was snapped off the bridging tabs on the electrical outlet isolating each receptacle.

I then wired the electrical outlet so that when the relay is in the NC position it is sending current to only one of the outlets.

When the relay switches to the NO position it switches power to the other outlet.

So what's happening is the fridge is plugged in to the (NC) energized outlet. When a certain set point is reached the relay switches to the other outlet (NO) which has a light bulb plugged into it.

Hope that makes sense.

So, you are going to either have the fridge on or the heater on at all times? Does not sound very efficient.

Forgot to mention that my fermentation fridge is out in my detached garage.

I'm also using a florescent bulb for my heat source.

If you know of a more efficient way of controlling my fermentation temps I would like to hear what you would suggest.

dmfa200 said:

Forgot to mention that my fermentation fridge is out in my detached garage.

I'm also using a florescent bulb for my heat source.

If you know of a more efficient way of controlling my fermentation temps I would like to hear what you would suggest.

Click to expand...

Using it as a two stage controller would be much better. Setting it up the way you describe is going to cause the fridge and light bulb to be constantly battling each other.

I use a BCS-460 set to run the Keezer at a constant temp, and then use brewbelts for the individual fermenters.

if the fridge thermostat is being used to control the cold end while plugged in, you essentially still have a single stage controller. By giving it power all the time you have essentially skipped the temp controller.

What you did isn't two stage control. All you did was increase the amount of energy it takes to run your fridge.